This work shows how the rate parameter of the proposed kinetic model is highly suitable for adequately comparing the temperature-dependent thermal stability behavior of different compounds. This means that a simple plot of the rate parameter versus temperature for polymers containing fillers of different natures or in different concentrations allows for establishing the temperature ranges in which each filler is more efficient in improving thermal stability. Since linear low-density polyethylene (LLDPE) is used in a wide range of applications, its thermal degradation is a crucial aspect to consider for its optimal use. This work examines the effect of magnesium hydroxide (MH) and multi-walled carbon nanotubes (MWCNTs) on the thermal degradation of LLDPE in a non-oxidizing atmosphere using isothermal data. Experimental data were obtained by thermogravimetry (TGA) in a nitrogen atmosphere at different temperatures. A kinetic study was performed using a model-fitting method based on logistic derivative functions. The method consists of initially fitting the experimental mass loss rate curves using nonlinear methods with logistic derivative functions. One of the fitting parameters represents the degradation rate. The kinetic significance is primarily described by the dependence of the rate parameter, used in the fittings, on the temperature. That dependence can be expressed in two equivalent ways: either by a characteristic time and temperature, or by the parameters of the classical Arrhenius equation—activation energy and pre-exponential factor. Ultimately, by comparing the kinetics of LLDPE and its composites, it was possible to establish the stabilizing effect of the fillers as a function of temperature. More importantly, this methodology provides a very clear and direct way to compare how the stabilizing effects of fillers of different natures and at different ratios vary across temperature ranges. The observed temperature-dependent stabilization effects in LLDPE composites underscore the critical need for precise filler selection tailored to specific operational temperature ranges, offering vital design guidelines for enhanced thermal management in practical applications.
A major challenge in polymer composite research is accurately predicting thermal degradation behavior under different heating conditions while effectively distinguishing primary polymer decomposition from filler-related mass loss. This study introduces a novel approach by employing a logistic derivative function fitting method, which allows for the clear separation of magnesium hydroxide (MH) dehydration from the main degradation of linear low-density polyethylene (LLDPE). Understanding the thermal stability of LLDPE composites is crucial for enhancing fire safety and long-term durability in industrial applications. This study investigates the effect of MH and multi-walled carbon nanotubes (MWCNTs) on the thermal degradation of LLDPE under a nitrogen atmosphere, using non-isothermal thermogravimetric analysis (TGA). Pure LLDPE (PE), LLDPE/MH (mPE), and LLDPE/MH/MWCNTs (mcPE) composites were tested at four heating rates (5, 10, 15, and 20 K min –1 ). The degradation kinetics were analyzed using ASTM E698 and Ozawa–Flynn–Wall classical methods, alongside a logistic-based model that enhances the accuracy of degradation predictions. The results revealed that while the main degradation process of LLDPE remains largely unchanged, secondary degradation reactions were effectively suppressed by the fillers. Additionally, the logistic model allowed for accurate estimation of degradation behavior at untested heating rates. This methodology provides a powerful tool for optimizing polymer composite formulations, particularly in cable insulation and fire-retardant coatings, where enhanced thermal stability is essential for safety and material longevity.
危险品化学品经营许可证（带存储）